An experiment using an animal is carried out in order to develop a novel medicine. An experimental animal is analyzed after being reared under a predetermined experimental environment. After rearing under the experimental environment, a long time may elapse before analysis. In addition, after the rearing and before the analysis, the animal may be placed under an environment different from the experimental environment. By the elapse of time and the placement under the different environment, a condition of the animal may change from a state under the experimental environment.
A technique for euthanizing and biologically fixing the animal to keep a condition of the animal to be in a state under the experimental environment is known. As such the technique, euthanasia/fixation means is described in “Summary of Report, “Feasibility Study for Development of Reentry Bioscience Small Experimental Satellite System”, The Mechanical Social Systems Foundation, March, 2008” (document 1).
FIG. 1 is a schematic view showing the euthanasia/fixation means described in document 1. The euthanasia/fixation means is mounted on a reentry experimental satellite shuttling between the ground and the space. The euthanasia/fixation means includes a cage 106, a liquid nitrogen tank 101, and a carbon dioxide tank 102. The cage 106 is provided for rearing a small animal and is covered with a heat insulating cooling mechanism 103. The carbon dioxide tank 102 is provided for euthanizing the small animal. The liquid nitrogen tank 101 is provided for fixing the small animal. In addition, an exhaust line 105 to which a relief valve 104 is attached is provided to the cage 106. After the reentry experimental satellite has been launched to the space, the small animal in the cage 106 is reared under a microgravity environment that is the experimental environment. Before the reentry, the carbon dioxide gas is supplied from the carbon dioxide tank 102 into the cage 106. In this manner, the small animal is suffocated and euthanized. In addition, cooled nitrogen gas is supplied from the liquid nitrogen tank 101 into the cage 106 via a temperature adjuster. In this manner, the small animal is cooled to be biologically fixed. The small animal is placed under a hyper gravity at the reentry to the ground. By placement under the hyper gravity, a condition of the small animal may change from a state where the animal was reared under the microgravity environment. However, by using the euthanasia/fixation means described in document 1, the state under the microgravity environment can be maintained because the small animal is fixed.